The use of machines, racks and various other types of devices for the purpose of exercising is old. Included among prior art exercise devices are platforms or benches for performing sit-ups, parallel bars for performing dips and weights. Exercise structures have evolved from the use of these devices primarily on a trial-and-error basis. In recent years, the trial and error approach to development of exercise structures has been giving way to more systematic studies conducted in a more scientific manner by researchers with strong academic backgrouds on appropriate groups, often times young men and women in schools and universities. From these studies have been identified certain principles that serve as guidelines for formulating programs intended to develop the body with specific objectives in mind. Some athletes aspire to be runners, other aspire to be swimmers, or wrestlers, etc. In general, manufacturers of exercise apparatus provide equipment with which one or more exercises can be performed without much regard to relating the value of an exercise to a specific activity. This is in spite of the fact that several important principles have come to be recognized as operative regarding the development of athletic prowess. Four of these principles are particularly germane to the objects of this invention:
1. The greatest rate of strength increase due to exercise is very specific to the range of motion in which the exercise is performed.
2. Rate of increase of strength is most rapid when a program of stress imposed by the exercise approaches the maximum capacity of the performer.
3. The rate of increase of running speed is most rapid when a program of strength building exercises is combined with speed building exercises.
4. Heavy resistance exercises, performed specifically in the range of motion where stress imposed by running is greatest, are very effective in protecting against injuries (to the hamstring, groin, Achilles' tendon, etc.)--often experienced by sprinters.
It is an object of this invention to provide an apparatus which enables the user to perform a number of exercises which particularly benefit the muscle groups involved in sprinting by applying adjustable resistance to the motion of said groups in the range of motion where stress in sprinting is greatest.
Maximum stress on the hamstring occurs when the foot strikes the ground almost directly under the center of gravity of the body. In the next instant, violent contractions of the hamstring and buttocks propel the body forward by pushing the foot backward. Thus, one important exercise to improve speed would involve contractions of the hamstring and buttocks when the hip is almost straight.
While the thrust with the hamstring is being performed, the muscles of the lower abdomen and upper part of the quadriceps of the same leg are relaxed and stretching to their fullest extent. At the instant the hamstring thrust is complete, and the foot is about to leave the ground, these stretched lower abdmoninal and upper quadricep muscles are suddenly called upon to contract in order to reverse the direction of the swing. From this consideration, it is apparent that a second important exercise would be one which causes contraction of the lower abdominal muscles when the back is arched. When one foot strikes the ground, the knee of the other leg starts its swing upward and forward. It is well known that the best sprinters have high knee action. Thrusting the kness as high as possible requires strong contraction of the abdominal muscles and quadriceps in that range of motion where the sprinter is in a jack-knife position. Stressed contractions with the body and legs "jack-knifed" is therefore a third important exercise.
Sprinting is a twisting action where the angular momentum generated by the hips and legs twisting in one direction is counter balanced by the arms and shoulders twisting in the opposite direction. Consequently, it is well recognized that total body strength including the arms and shoulders is important for top sprinters. Exercises for the arms and upper back in the aforedescribed ranges of motion can be performed with the apparatus of this invention.
As the muscle group becomes stronger, it is desireable to increase the resistance to motion of the exercise in accordance with the principle of maximum exertion for greatest rate of strength gain. Most exercise machines have means for lifting various amounts of weight to provide added resistance while others have springs, or use compressed air or hydraulics. Weights are expensive. Springs wear. Therefore, while the use of weights and springs together with said apparatus is intended to be an embodiment of this invention, a preferred embodiment will be presented which uses the weight of the apparatus and the performer with adjustable leverage to apply variable resistance.
The most effective way to reach the market with this type of equipment is by mail orders generated by TV or news advertisements or by consigning large numbers to chain stores. Therefore, the preferred situation in the interest of reducing shipping and storage costs is to sell the apparatus dissembled and packaged in compact containers. This requires that the buyer be able to assemble the apparatus with a few common tools and that the apparatus be very sturdy for this purpose.
It is therefore a further objective of this invention that said apparatus be capable of being packaged in a compact flat package and easily assembled by the user.